Computer Drawing of Micro-spectrometer (IMAGE) Eindhoven University of Technology Caption The blue perforated slab is the upper membrane, with the photonic crystal cavity in the middle. This captures the light of a specific near infrarad frequency and generates a current that is measured (A). If the distance to the red, lower slab is changed, the captured frequency changes. Credit Eindhoven University of Technology. Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.